1. Field of the Invention
The present invention relates to a diamino compound, an intermediate thereof and a production process for the same.
2. Description of the Related Art
A twist nematic (hereinafter abbreviated as TN) mode having a structure in which an aligning direction of nematic liquid crystal molecules is twisted by 90 degrees between electrode substrates which constitute a pair by two sheets is mainly adopted for a liquid crystal display element used for watches and electronic potable calculators. Further, a super twisted nematic (hereinafter abbreviated as STN) mode in which a twisted angle is increased to 180 to 300 degrees is developed as well, and a liquid crystal display element providing a good display quality as well in a large picture plane has come to be obtained.
Further, matrix display and color display have come to be prevailing in recent years, so that an MIM (metal-insulating phase-metal) element and a TFT (field effect type thin film transistor) element in which a lot of picture element electrodes and an active type twisted nematic mode capable of switching them on and off are adopted have come to be actively developed.
A problem which is common to all these modes is that caused is a phenomenon called burning in which another picture is displayed on a picture plane after displaying the same picture for long time and then the preceding picture remains thereon as an after-image. In particular, in order to obtain a liquid crystal display element having a high grade, it is a very important subject to prevent this burning phenomenon.
This burning is considered to be caused in such a manner that a direct current component applied to a liquid crystal display element produces an electric double layer due to an ion component of impurities contained in liquid crystal on the surface of an alignment film to bring about a deviation of charges between upper and lower substrates and this deviation, which is stably maintained, results in producing a potential difference. In particular, in a TFT element, a direct current component can not be removed due to the characteristics of the element, and therefore burning is liable to be more conspicuous than those of TN and STN elements and is serious.
Further, in order to prevent flickering on a picture plane due to an after-image, required in a TFT mode is an alignment film having a high voltage-holding rate even at 60 to 90xc2x0 C. at which the voltage-holding rate is particularly notably reduced.
In a liquid crystal display element, a variation in a pretilt angle by heat leads to a change in a threshold voltage, and therefore a stability of the pretilt angle after a long-term reliability test at a high temperature is a very important element as well.
Organic base films of polyimide and polyamide are mainly used as an alignment film used for such liquid crystal display element, and it is described in Japanese Patent Application Laid-Open No. 65960/1976 that a polyesterimide polymer film is provided on an electrode substrate by a dimethyl acetamide solution of a polyamic acid which is a precursor of polyesterimide obtained by condensing 4,4xe2x80x2-diaminodiphenyl ether with an aromatic dicarboxylic anhydride obtained from trimellitic acid and hydroquinone and that this is subjected to aligning treatment to prepare a liquid crystal device. An element using a polyimide alignment film obtained by using such polyether compound is liable to cause burning.
An object of the present invention is to solve the problems described above and provide a diamino compound suitable for obtaining a polyimide capable of forming a liquid crystal alignment film capable of providing a liquid crystal display element which has a small burning phenomenon that is a small after-image and a high voltage-holding rate over a low temperature through a high temperature and which has a high pretilt angle and less change in the pretilt angle after a long-term reliability test at a high temperature, an intermediate therefor and a production process for the same.
Intensive research and development promoted by the present inventors have resulted in finding a diamino compound having such specific structure that, through burning and a voltage-holding rate are correlated with polarity on the surface of an alignment film, this polarity can be reduced. Further, they have found that an alignment film in which a burning phenomenon on the picture plane is reduced and a high voltage-holding rate is held over a low temperature through a high temperature and in which a variation in a pretilt angle is inhibited even after a long-term reliability test at a high temperature can obtained by using this diamino compound as a polyimide raw material for the alignment film. Thus, they have completed the present invention.
1) The diamino compound of the present invention is represented by Formula (1): 
(wherein A1 represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; A2 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and one. or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; one amino group is bonded to any position in the ring; m represents an integer of 0 to 3, and n represents an integer of 1 to 5). It is preferably a diamino compound represented by the following Formula (1xe2x80x2): 
2) The diamino compound of the present invention which is more specifically shown is represented by Formula (2): 
(wherein R represents a linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 11 carbon atoms or a hydrogen atom; m represents an integer of 0 to 3, and y represents an integer of 0 to 5; and preferably, m is 1 to 2, and y is 0). It is more preferably a diamino compound represented by the following Formula (2xe2x80x2): 
(wherein R represents a linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 11 carbon atoms or a hydrogen atom).
3) A production process for the diamino compound of the present invention is characterized by reacting a cyclohexylbenzene derivative represented by Formula (3): 
(wherein A1 represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; A2 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; and m represents an integer of 0 to 3) with an acid halide represented by Formula (4): 
(wherein X represents any of a bromine atom and a chlorine atom; one nitro group is bonded to any position in the ring; and n represents an integer of 1 to 5) by the Frieldel-Crafts reaction to produce a cyclohexylphenylcarbonyl compound represented by Formula (5): 
(wherein the respective marks are synonymous with those described above), and reducing the above compound after nitrating, whereby the compound represented by Formula (1): 
(wherein one amino group is bonded to any position in the ring, and the others are synonymous with those described above) is obtained.
A preferred method of the preceding reduction after nitration comprises nitrating the cyclohexylphenylcarbonyl compound represented by Formula (5) to synthesize a compound represented by Formula (6): 
(wherein the respective marks are synonymous with those described above), then reducing the carbonyl group to thereby synthesize a dinitro compound represented by Formula (7): 
(wherein the substituents are synonymous with those described in Formula (6)), and reducing these nitro groups.
4) The cyclohexylphenylcarbonyl compound of the present invention is represented by Formula (5): 
(wherein A1 represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; A2 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; one nitro group is bonded to any position in the ring; m represents an integer of 0 to 3, and n represents an integer of 1 to 5).
5) A production process for the cyclohexylphenylcarbonyl compound of the present invention is characterized by reacting the cyclohexylbenzene derivative represented by Formula (3): 
(wherein A1 represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; A2 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and one or optional methylene groups which are not adjacent in the group may be substituted with an oxygen atom; and m represents an integer of 0 to 3) with the acid halide represented by Formula (4): 
(wherein X represents any of a bromine atom and a chlorine atom; one nitro group is bonded to any position in the ring; and n represents an integer of 1 to 5) by the Frieldel-Crafts reaction to obtain the cyclohexylphenylcarbonyl compound represented by Formula (5): 
(wherein the respective marks are synonymous with those described above).